The Agilent Varian two stage, direct drive, rotary vane mechanical pump incorporates hardened steel rotors, positively lubricated and frictionless hydrodynamic bearings, and stainless steel vane springs and filters. The spring loaded vanes do not rely on centrifugal force for sealing. An anti suckback valve with its integral rubber seal prevents oil from migrating back into the vacuum system should the motor be stopped inadvertently.